Dishwasher and method for cleaning wash ware

ABSTRACT

A method, and related dishwasher, for cleaning wash ware that provides a wash phase followed by a rinse phase, in which rinse fluid is conducted into a treatment chamber ( 2 ) of the dishwasher ( 1 ). The rinse phase is composed of a fresh-water rinse phase and a steam rinse phase. During the fresh-water rinse phase, a rinse liquid is sprayed into the treatment chamber ( 2 ). During the steam rinse phase, steam is generated and conducted into the treatment chamber ( 2 ). A total of 0.5 to 2.0 litres of rinse fluid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber ( 2 ) in a top view of the treatment chamber, and preferably 1.0 to 1.7 litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosed by the wall of the treatment chamber ( 2 ) in a top view of the treatment chamber, is sprayed into the treatment chamber ( 2 ) during the fresh-water rinse phase.

The invention relates to a dishwasher and to a method for cleaning washware in a dishwasher.

The invention relates, in particular, to a method for cleaning wash warein a dishwasher, in particular a commercial dishwasher, which is in theform of a program-controlled ware washer. Furthermore, the inventionrelates to a dishwasher, in particular a commercial dishwasher, in theform of a program-controlled ware washer.

Programme-controlled ware washers are dishwashers which can be manuallyloaded and unloaded. Programme-controlled ware washers (called box-typeware washers or even batch dishwashers) may be called hood-typedishwashers or even hood-type ware washers or may be front loaderdishwashers (front loader ware washers). Front loader dishwashers may beunder-counter machines, top-counter machines or else free-standing frontloaders.

Examples of wash ware include plates, cups, pots, trays, knives, forks,spoons, glasses and other kitchen utensils.

WO 2006/037447 A1 discloses a dishwasher in the form of aprogram-controlled ware washer, in which the following method steps arerun through successively: a wash phase, in which wash liquid is sprayedfrom a tank by means of wash pump through a wash line system into atreatment chamber and can flow back from the treatment chamber into thetank because of the force of gravity; a rinse phase, in which heatedfresh water as the rinse liquid is sprayed from a fresh-water feed lineby means of a rinse pump through a rinse line system into the treatmentchamber and can flow from the treatment chamber into the tank because ofthe force of gravity; a steam phase, in which steam is generated fromheated fresh water from a fresh-water feed line by means of a steamgenerator and is conducted into the treatment chamber by the rinse linesystem. Provision is optionally made for the wash ware to be dried afterthe steam phase by air being blown in or to be cooled by letting waterin. A booster can alternatively be used to heat up the fresh water forthe rinsing or for steam generation.

EP 1 738 677 A2 discloses a domestic dishwasher which is designed forthe following procedure: a wash phase, during which wash liquid issprayed by means of a pump from a sump via spray nozzles into a washingchamber which is designed to accommodate wash ware. Wash liquid is thenpumped away, and the sump is filled with fresh water which is thenconveyed by the same pump as the wash liquid previously to the samespray nozzles as the wash liquid previously. The transition from thesump to the pump contains a heater for heating the wash liquid, with itbeing possible for the rinse liquid to be heated or left unheated duringthe rinse phase. The rinse phase is followed by a steam phase, in whichfresh water from the sump is evaporated by means of the heater and isconducted via the said spray nozzles into the treatment chamber. Thesteam phase may be followed by a drying phase, in which the heated washware dries.

Commercial dishwashers require water, detergent, rinse aid and energy inorder to clean wash ware. The consumption of detergent and rinse aid isproportionally dependant on the water consumption per wash cycle. Thisis also true of the heating energy at a constant water admissiontemperature.

A commercial dishwasher usually has two water circuits which arecompletely separate from each other. These two water circuits comprise acircuit which is responsible for washing and through which used waterfrom the wash tank is conducted, and a fresh-water circuit which isresponsible for rinsing and uses fresh water from a boiler.

The main object of the rinse phase is to remove the wash-liquid residues(lye) which are found on the wash ware. The rinse liquid (pure freshwater or fresh water mixed with rinse aid) which is sprayed during therinse phase flows into the wash tank and then also serves to regeneratethe wash liquid.

Before new rinse liquid is conducted into the wash tank during the rinsephase, the same quantity of wash liquid is pumped out of the wash tank.

At the basis of conventional dishwashers which are known from the priorart and are in the form of program-controlled ware washers is afresh-water or rinse-liquid consumption of 2.4 to 3.5 litres per washcycle.

The object to be achieved by the invention is to provide a way ofreducing the quantity of fresh water and quantity of rinse liquidrequired for cleaning wash ware, without the efficiency of the cleaningof the wash ware being adversely affected.

The invention achieves this object by means of a method for cleaningwash ware in a dishwasher, in particular in a commercial dishwasher,which is in the form of a program-controlled ware washer and has atreatment chamber for accommodating the wash ware which is to becleaned, wherein the method has the following program-controlled methodsteps which are to be executed successively: a wash phase, in which washliquid is sprayed from a tank (wash tank) by means of a wash pumpthrough a wash line system into the treatment chamber and can flow backinto the tank from the treatment chamber because of the force ofgravity; and a rinse phase, in which rinse fluid is conducted into thetreatment chamber.

The term “rinse fluid” used here is to be understood as meaning anygaseous or vaporous or liquid substance which is sprayed into thetreatment chamber of the dishwasher during the rinse phase or issupplied to the treatment chamber of the dishwasher in some other way,with the aim of removing the wash-liquid residues (lye) which are to befound on the wash ware after the wash phase.

With regard to the method for cleaning wash ware, the present inventionis characterized in that the rinse phase is composed of a fresh-waterrinse phase and a steam rinse phase. During the fresh-water rinse phase,a rinse liquid is sprayed from a rinse-liquid supply device by means ofa rinse pump through a rinse line system into the treatment chamber ofthe dishwasher. The rinse liquid sprayed into the treatment chamberduring the fresh-water rinse phase can subsequently flow into the washtank of the dishwasher because of the force of gravity. A suitablerinse-liquid supply device, from which the rinse liquid is removedduring the fresh-water rinse phase, is, in particular, a fresh-watertank, in which fresh water and, if appropriate, rinse aid which ismetered into the fresh water are stored, or a boiler, in which the rinseliquid (i.e. the fresh water and the rinse aid which, if appropriate, ismetered into the fresh water) can optionally be heated.

During the steam rinse phase, rinse liquid (i.e. pure fresh water orfresh water with rinse aid metered in) is evaporated with the aid of asteam generator connected to a fresh-water feed line, and the steamgenerated in such a manner is conducted into the treatment chamber ofthe dishwasher.

It is provided here, as being particularly essential to the invention,that a total of 0.5 to 2.0 litres of rinse liquid per unit area of 500mm×500 mm, which is enclosed by the wall of the treatment chamber in atop view of the treatment chamber, and preferably a total of 1.0 to 1.7litres of rinse liquid per unit area of 500 mm×500 mm, which is enclosedby the wall of the treatment chamber in a top view of the treatmentchamber, are sprayed into the treatment chamber of the dishwasher duringthe fresh-water rinse phase.

The abovementioned rinse-liquid quantities are each based on a unit areaof 500 mm×500 mm, since the accommodating capacity of a dishwasher inthe form of a program-controlled ware washer is usually described or canbe described with the aid of the unit area size of 500 mm×500 mm. Thisunit area size is derived from the area of a utensil basket customarilyused in a dishwasher.

As a rule, the area of a utensil basket used for inserting the wash wareinto the treatment chamber of the dishwasher is 500 mm×500 mm. Adishwasher, the treatment chamber of which is designed for accommodatinga single utensil basket, is therefore approximately 500 mm×500 mm insize in a top view of the treatment chamber. A dishwasher which isdesigned for simultaneously accommodating two utensil baskets thereforehas a treatment chamber which has, in a top view of the treatmentchamber, an area which is enclosed by the wall of the treatment chamberand corresponds to two unit areas of 500 mm×500 mm.

The present invention is based on the finding that the steam conductedinto the treatment chamber during the steam rinse phase can be used forremoving residue wash liquid, in particular lye, from the surfaces ofthe wash ware. Accordingly, it is possible for only some of thewash-liquid residues remaining on the surfaces of the wash ware afterthe wash phase to be rinsed off during the fresh-water rinse phase, bythe rinse liquid being sprayed into the treatment chamber of thedishwasher. The remaining amount of wash-liquid residues is removed withthe aid of the steam conducted into the treatment chamber of thedishwasher during the steam rinse phase.

Owing to the fact that, according to the invention, the rinse phase iscomposed, firstly, of a fresh-water rinse phase and, secondly, of asteam rinse phase, the total water consumption per cleaning cycle can bereduced, with the energy to be applied per cleaning cycle and thechemical costs being reduced at the same time.

Tests have shown that steam which condenses on the surfaces of wash warehas extremely good rinsing-off effects. The steam introduced into thetreatment chamber of the dishwasher during the steam rinse phase isdistributed uniformly in the treatment chamber in accordance with thesecond fundamental law of thermodynamics, and therefore said steam whichis introduced into the treatment chamber in particular even reacheswash-ware shadow zones which may possibly be present, i.e. surfaces ofthe wash ware which are not directly reachable by the spray jet. Putanother way, this means that the steam introduced into the treatmentchamber of the dishwasher during the steam rinse phase reaches everysurface of the wash ware within the treatment chamber irrespective ofthe position and the orientation of the surface of the wash ware and canbe deposited substantially in equal parts (uniformly) on the surfaces ofthe wash ware. This advantageous effect cannot be achieved in the caseof a rinse phase which merely comprises a fresh-water rinse phase, inwhich rinse liquid rather than any steam is sprayed into the treatmentchamber.

Surfaces of wash ware, which, on account of their geometrical shape, donot permit fluid to flow off from them because of gravity, i.e. do notpermit liquid to flow off from them because of the force of gravity,provide restrictions with regard to the use of steam as a rinsingmedium. These restrictions may occur, for example, in the case of washware having depressions in the base, such as, for example, in the caseof small bowls or glasses, if said wash ware is correspondinglypositioned in the treatment chamber of the dishwasher and theorientation of at least some of the surfaces of the wash ware does notpermit liquid to flow off from them in a gravity-induced manner.

The restriction discussed above means that a steam rinse phase alone is,under some circumstances, not sufficient as a rinse phase to achieve agood cleaning result. For this reason, according to the presentinvention, the rinse phase used for rinsing off the wash-liquid residuesremaining on the surfaces of the wash ware after the wash phase iscomposed of the steam rinse phase and the fresh-water rinse phase. Ithas been shown that only the combination of a fresh-water rinse phaseand a steam rinse phase supplies a thoroughly satisfactory cleaningresult.

In comparison to a rinse phase carried out in a conventional dishwasherknown from the prior art, with the solution according to the invention,in which the fresh-water rinse phase is employed in conjunction with thesteam rinse phase, the quantity of fresh water used in total during therinse phase can be significantly reduced.

In a preferred realization of the method according to the invention, itis provided that a standard wash phase is followed by the previouslydescribed fresh-water rinse phase carried out with a reduced quantity offresh water of 0.5 to 2.0 litres, and preferably with a reduced quantityof fresh water of 1.0 to 1.7 litres. This fresh-water rinse phase isfollowed by the steam rinse phase, in which the wash-liquid residuesstill remaining on the surfaces of the wash ware after the fresh-waterrinse phase are completely rinsed off with the aid of the steamintroduced into the treatment chamber of the dishwasher. This steamrinse phase employs a total quantity of fresh water of 0.05 to 0.25litre, and preferably a quantity of fresh water of 0.10 to 0.15 litre insteam form. The quantities of fresh water stated for this preferredrealization of the solution according to the invention are always basedon a dishwasher in the form of a program-controlled ware washer, thetreatment chamber of which is designed for a utensil basket of 500mm×500 mm, and therefore a unit area of 500 mm×500 mm is enclosed by thewall of the treatment chamber in a top view of the treatment chamber.

In the abovementioned, preferred realization of the solution accordingto the invention, the steam rinse phase lasts for a total ofapproximately 5 to 60 seconds, and preferably for a total ofapproximately 10 to 30 seconds.

Following the steam rinse phase, a condensation and draining phase isthen carried out, which phase lasts for a defined time, and in which thesteam conducted into the treatment chamber of the dishwasher during thesteam rinse phase can at least partially condense on the surfaces of thewash ware, can drain and flow into the wash tank because of the force ofgravity. The abovementioned condensation and draining phase preferablylasts for approximately 10 to 60 seconds, and even more preferablyapproximately 20 to 30 seconds.

In comparison to the currently customary cleaning methods used indishwashers—in the case of the abovementioned preferred realization ofthe method according to the invention, approx. 1 litre of fresh waterand a corresponding quantity of detergent and rinse aid and approx. 50to 200 kJ of energy can be saved per wash or rinsing cycle.

The object on which the invention is based is achieved with regard tothe apparatus by means of a dishwasher, in particular by means of acommercial dishwasher, in the form of a program-controlled ware washerwhich is designed for executing the above-described method according tothe invention. In this case, the dishwasher has a program-control devicefor executing at least one cleaning program; a treatment chamber intowhich wash ware can be manually inserted and from which said wash warecan be removed; a tank (wash tank) down into which liquid from thetreatment chamber can flow because of the force of gravity; a washsystem with a wash pump and a wash line system for conveying wash liquidfrom the wash tank through wash nozzles into the treatment chamberduring a wash phase; a fresh-water rinse system with at least one rinsepump and at least one rinse line system for conveying rinse liquid froma fresh-water supply device through rinse nozzles into the treatmentchamber during a fresh-water rinse phase; and a steam rinse system witha steam generator, which is connected to a fresh-water feed line, forgenerating steam and for conducting the steam via a steam line into thetreatment chamber during a steam rinse phase. In this case, theprogram-control device is designed in such a manner that first the washphase, then the fresh-water rinse phase and thereafter the steam rinsephase are executed.

The dishwasher according to the invention is distinguished in that theprogram-control device and the fresh-water rinse system controlled by itare designed to spray a total of 0.5 to 2.0 litres of rinse liquid perunit area of 500 mm×500 mm, which is enclosed by the wall of thetreatment chamber in a top view of the treatment chamber, and preferablya total of 1.0 to 1.7 litres of rinse liquid per unit area of 500 mm×500mm, which is enclosed by the wall of the treatment chamber in a top viewof the treatment chamber, during the fresh-water rinse phase.

The invention is described below using preferred embodiments of thedishwasher according to the invention with reference to the attacheddrawings, in which

FIG. 1 schematically shows a dishwasher, in particular a commercialdishwasher, in the form of a program-controlled ware washer, accordingto a first embodiment; and

FIG. 2 schematically shows a dishwasher, in particular a commercialdishwasher, in the form of a program-controlled ware washer, accordingto a second embodiment.

The dishwasher 1 according to the invention contains a treatment chamber2 for cleaning wash ware (not illustrated). A wash tank 4 in whichliquid can flow back out of the cleaning chamber 2 because of the forceof gravity is arranged under the treatment chamber 2. The wash tank 4can be covered at the transition to the treatment chamber 2 with the aidof a strainer (not illustrated). The wash tank 4 contains wash liquid 6,which is usually water, to which detergent can optionally beautomatically supplied by a detergent-metering apparatus (notillustrated). The wash liquid 6 can be conveyed by a wash pump 8 via awash line system 10 to wash nozzles 7 and 9 and can be sprayed throughsaid wash nozzles 7, 9 in the treatment chamber 2 onto the wash ware tobe cleaned. The sprayed wash liquid 6 subsequently flows back into thewash tank 4. A discharge line 3 with a discharge pump 11 can beconnected to the lower end 5 of the wash tank for the purpose ofemptying the wash tank 4, if the need arises.

In the embodiment, illustrated in FIG. 1, of the dishwasher 1 accordingto the invention, the intake side of a first rinse pump 12 is connectedto an outlet 35 of a boiler 21. The boiler 21 furthermore has an inlet22 which is connected to a fresh-water feed line 28 and via which eitherfresh water or fresh water with rinse aid metered into it is supplied tothe boiler 21. In the boiler 21, the liquid (pure fresh water or freshwater with rinse aid metered into it) which is supplied via the inlet 22is heated up in accordance with the stipulations of a process sequence.Via the first rinse pump 12, the intake side of which is connected tothe boiler outlet 35, the rinse liquid which is heated up in the boiler21 can be supplied, for example during a fresh-water rinse phase, via arinse line system 15, 15 a to rinse nozzles 33 and 34, respectively. Therinse nozzles 33 and 34 are arranged in the treatment chamber 2 in orderto spray the rinse liquid heated in the boiler 21 onto the wash ware inthe treatment chamber 2. Of course, however, it is also conceivable forthe boiler 21 to be supplied via the inlet 22 and the fresh-water feedline 28 with pure fresh water into which a rinse aid is metered afterthe fresh water has been heated in the boiler 21.

Furthermore, in the embodiment, illustrated in FIG. 1, of the dishwasher1 according to the invention, a second rinse pump 13 is provided, theintake side of which is connected to a fresh-water tank 14 and thedelivery side of which is connected to a rinse line system 15, 15 b. Therinse line system 15 b which extends from the delivery side of thesecond rinse pump 13, and the rinse line system 15 a which extends fromthe delivery side of the first rinse pump 12 merge into a common rinseline system 15. By means of the second rinse pump 13 which is connectedto the fresh water tank 14, unheated rinse liquid can be conveyed to therinse nozzles 33 and 34 arranged in the treatment chamber 2 in order tospray unheated rinse liquid onto the wash ware, if the need arises.

The fresh-water tank 14 has an inlet 37 which is connected to afresh-water feed line 31. Either pure fresh water or fresh water withrinse aid metered into it is supplied via this fresh-water feed line 31to the fresh-water tank 14. Of course, however, it is also conceivableto arrange, downstream of the outlet 36 of the fresh-water tank 14, ametering device, not illustrated in FIG. 1, for the metering in of rinseaid.

The wash nozzles 7, 9 and the rinse nozzles 33, 34 are respectivelypreferably arranged above and below the wash ware region and directedtowards the wash ware region of the treatment chamber 2. In theembodiment, illustrated in FIG. 1, of the dishwasher 1 according to theinvention, an upper wash-nozzle system and an upper rinse-nozzle systemformed separately therefrom, and a lower wash-nozzle system and a lowerrinse-nozzle system formed separately therefrom are provided. Of course,however, it would also be conceivable to provide an upper and a lowerwash-nozzle system which together serve to spray wash liquid and tospray rinse liquid. Instead of being arranged at the bottom and top, thewash nozzles 7, 9 and/or the rinse nozzles 33, 34 may also be arrangedonly at the top or only at the bottom, or instead or in addition, alsoon one side of the treatment chamber 2 and directed into the wash wareregion transversely with respect to the treatment chamber 2.

In the embodiment, illustrated in FIG. 1, of the dishwasher 1 accordingto the invention, both the boiler 21 and the fresh-water tank 14 areconnected via fresh-water feed lines 24, 26, 28, 29 and 31 to areturn-prevention means 16. The return-prevention means 16 serves toprevent fresh water from being able to sucked back into a fresh-waterfeed line 17 from the intake side of the first rinse pump 12 and/or fromthe intake side of the second rinse pump 13.

The return-prevention means 16 has an outlet 40 which is connected viafresh-water feed lines 24 and 41 to a water-softening device 39. Thewater-softening device 39 has, firstly, a salt container 42 which isconnected to the fresh-water feed line 41 and, secondly, first andsecond water softeners 39 a, 39 b which are arranged parallel to eachother. The two water softeners 39 a, 39 b which are arranged parallel toeach other are connected via a corresponding fresh-water line system andthe fresh-water feed line 24 to the outlet 40 of the return-preventionmeans 16. The water softeners 39 a, 39 b of the water-softening device39 can be operated alternately by suitable activation of the valves 43,in order to soften the fresh water supplied to the boiler 21 via thefresh-water feed lines 26 and 28 and to soften the fresh water suppliedto the fresh-water tank 14 via the fresh-water feed lines 26, 29 and 31.

The salt container 42 belonging to the water-softening device 39contains a suitable salt or a suitable chemical with which, when theneed arises, a water-softening agent metered in via the water softeners39 a and 39 b or a decomposition product produced when a water-softeningagent is metered in can be suitably regenerated. The salt container 42can be topped up with the salt or the chemical from the treatmentchamber 2 of the dishwasher 1 via an opening which can be closed by acover 44.

In the illustrated and preferred embodiment of the dishwasher 1according to the invention, the boiler 21 has an integrated steamgenerator 20. A corresponding steam outlet 23 of the steam generator 20is formed on the upper region of the boiler 21. The steam outlet 23 ofthe steam generator 20 is connected via a steam line 32 to the treatmentchamber 2 at a location 37 above the wash tank 4 in order, when the needarises, to conduct the steam generated in the steam generator 20 intosaid treatment chamber. The outlet opening of the steam line 32 ispreferably located between the upper nozzles 7, 33 and the lower nozzles9, 34 of the wash line system 10 and of the rinse line system 15. Ofcourse, however, other positions are also possible.

The boiler 21, which serves not only to heat the rinse liquid but alsoto generate steam, contains a heater 45. Furthermore, a level sensor 46which controls, for example, a valve 19 of the fresh-water line 17 maybe arranged in or on the boiler.

In the preferred embodiment, illustrated in FIG. 1, of the dishwasher 1according to the invention, it is optionally possible, by means of theprovision of the fresh-water tank 14 and the second rinse pump 13, alsoto supply non-heated rinse liquid via the rinse line system 15 b and 15to the rinse nozzles 33 and 34, respectively. Accordingly, it ispossible, by means of suitable activation, for example of the rinsepumps 12, 13, and/or by means of suitable activation, for example of thevalves 19, 27 and 30 arranged in the fresh-water feed lines to thefresh-water tank 14 and the boiler 21, to supply non-heated or heatedrinse liquid to the treatment chamber 2.

A program-control device 50 for controlling at least one cleaningprogram is designed in such a manner and is connected to thecontrollable components of the dishwasher, for example to the valves 19,27 and 30, to the wash pump 8, to the first rinse pump 12, to the secondrinse pump 13, and/or to a heater control circuit for controlling theheater 45, in order to realize a cleaning method (cleaning cycle) withthe following steps (phases) to be executed successively:

-   -   1. A wash phase, in which wash liquid is sprayed from the wash        tank 4 by means of the wash pump 8 through the wash line system        10 into the treatment chamber 2 and can then flow back into the        wash tank 4 from the treatment chamber 2 because of the force of        gravity;    -   2. A fresh-water rinse phase, in which heated or unheated fresh        water or fresh water with rinse aid metered into it, as the        rinse liquid, is sprayed by means of the first rinse pump 12 and        the second rinse pump 13 into the treatment chamber 2 and can        then flow into the wash tank 4 from the treatment chamber 2        because of the force of gravity; and    -   3. A steam rinse phase, which follows the fresh-water rinse        phase and in which steam generated by the steam generator 20 is        introduced into the treatment chamber 2 via the steam line 32,        which is formed separately from the wash line system 10 and        separately from the rinse line system 15.

Furthermore, the program controller 50 is preferably designed in such amanner that a condensation and draining phase is executed for a specificperiod of time in a program-controlled manner following the steam rinsephase, during which period of time steam introduced into the treatmentchamber 2 during the steam rinse phase can condense and can drain fromthe treatment chamber 2 into the wash tank 4, before the end of theprogram is reached.

FIG. 2 schematically provides a dishwasher, in particular a commercialdishwasher, in the form of a program-controlled ware washer according tothe second preferred embodiment of the solution according to theinvention. In contrast to the first embodiment illustrated in FIG. 1,the dishwasher 1 illustrated in FIG. 2 does not have a fresh-water tankand therefore also does not have a second rinse pump via which—asillustrated in FIG. 1—unheated rinse liquid can be supplied via a rinseline system to the rinse nozzle. Otherwise, the dishwasher 1 illustratedin FIG. 2 is identical in a structural and functional regard with thedishwasher described previously with reference to FIG. 1.

Of course, it is conceivable that the heater control circuit (notillustrated explicitly) can correspondingly activate the heater 45 ofthe boiler 21 or of the steam generator 20 in order to provide rinseliquid which is heated to a greater or lesser extent.

The invention is not restricted to the embodiments of the dishwasher 1that are shown by way of example in the drawings. On the contrary, theinvention arises from an expert overall consideration of the patentclaims and the description of the exemplary embodiments.

1. Method for cleaning wash ware in a program-controlled ware washerhaving a treatment chamber (2) for accommodating the wash ware to becleaned, wherein the method has the following program-controlled methodsteps to be executed successively: a wash phase, in which wash liquid(6) is sprayed from a tank (4) by means of a wash pump (8) through awash line system (10) into the treatment chamber (2) and can flow backinto the tank (4) from the treatment chamber (2) because of the force ofgravity; and a rinse phase, in which rinse fluid is conducted into thetreatment chamber (2), characterized in that the rinse phase is composedof a fresh-water rinse phase, in which a rinse liquid is sprayed from arinse-liquid supply device (14, 21) by means of a rinse pump (12, 13)through a rinse line system (15) into the treatment chamber (2) and canflow from the treatment chamber (2) into the tank (4) because of theforce of gravity, and of a steam rinse phase, in which steam isgenerated by means of a steam generator (20), which is connected to afresh-water feed line (28), and is conducted into the treatment chamber(2), with a total of 0.5 to 2.0 litres of rinse liquid per unit area of500 mm×500 mm, which is enclosed by the wall of the treatment chamber(2) in a top view of the treatment chamber, being sprayed into thetreatment chamber (2) during the fresh-water rinse phase.
 2. Methodaccording to claim 1, characterized in that a total water quantity of0.05 to 0.25 litre per unit area of 500 mm×500 mm, which is enclosed bythe wall of the treatment chamber (2) in a top view of the treatmentchamber, is conducted in steam form during the steam rinse phase intothe treatment chamber (2).
 3. Method according to claim 2, characterizedin that 1.0 to 1.7 litres of rinse liquid per unit area of 500 mm×500mm, which is enclosed by the wall of the treatment chamber (2) in thetop view of the treatment chamber is sprayed into the treatment chamber(2) during the fresh-water rinse phase and water quantity of 0.10 to0.15 litres per unit area of 500 mm×500 mm, which is enclosed by thewall of the treatment chamber (2) in the top view of the treatmentchamber is conducted in steam form during the steam rinse phase into thetreatment chamber (2).
 4. Method according to claim 1, characterized inthat the steam rinse phase takes up a period of time of 5 to 60 seconds.5. Method according to claim 1, characterized in that the steam rinsephase begins after the fresh-water rinse phase ends.
 6. Method accordingto claim 1, characterized in that the steam rinse phase and thefresh-water rinse phase at least partially overlap chronologically. 7.Method according to claim 1, characterized in that the methodfurthermore has a condensation and draining phase which is carried outfollowing the steam rinse phase and lasts for a defined time, and inwhich the steam conducted into the treatment chamber (2) during thesteam rinse phase can at least partially condense, drain and flow intothe tank (4) because of the force of gravity.
 8. Method according toclaim 1, characterized in that clean fresh water is used as the rinseliquid during the fresh-water rinse phase, or in that fresh water andthe rinse aid which is metered into the fresh water are used as therinse liquid during the fresh-water rinse phase.
 9. Method according toclaim 1, characterized in that rinse liquid which is heated or unheatedduring the fresh-water rinse phase is sprayed into the treatment chamber(2).
 10. (canceled)
 11. Dishwasher (1) in the form of aprogram-controlled ware washer, having: a program-control device (50)for executing at least one cleaning program; a treatment chamber (2)into which wash ware can be manually inserted and from which said washware can be manually removed; a tank (4) down into which liquid from thetreatment chamber (2) can flow because of the force of gravity; a washsystem (7, 8, 9, 10) with a wash pump (8) and a wash line system (10)for conveying wash liquid (6) from the tank (4) through wash nozzles (7,9) into the treatment chamber (2) during a wash phase; a fresh-waterrinse system (12, 13, 15 a, 15 b, 33, 34) with at least one rinse pump(12, 13) and at least one rinse line system (15 a, 15 b) for conveyingrinse liquid from a fresh-water supply device (14, 21) through rinsenozzles (33, 34) into the treatment chamber (2) during a fresh-waterrinse phase; and a steam rinse system (20, 32) with a steam generator(20), which is connected to a fresh-water feed line (28), for generatingsteam and conducting the steam via a steam line (32) into the treatmentchamber (2) during a steam rinse phase, wherein the program-controldevice (50) is designed in such a manner that first the wash phase, thenthe fresh-water rinse phase and thereafter the steam rinse phase areexecuted, characterized in that the program-control device (50) and thefresh-water rinse system (12, 13, 15 a, 15 b, 33, 34) controlled by itare designed to spray a total of 0.5 to 2.0 litres of rinse liquid perunit area of 500 mm×500 mm, which is enclosed by the wall of thetreatment chamber (2) in a top view of the treatment chamber, into thetreatment chamber (2) during the fresh-water rinse phase.
 12. Dishwasheraccording to claim 11, characterized in that the program-control device(50) and the steam rinse system (20, 32) controlled by it are designedto conduct a total water quantity of 0.05 to 0.25 litre per unit area of500 mm×500 mm, which is enclosed by the wall of the treatment chamber(2) in a top view of the treatment chamber, in steam form into thetreatment chamber (2) during the steam rinse phase.
 13. Dishwasheraccording to claim 12, characterized in that 1.0 to 1.7 litres of rinseliquid per unit area of 500 mm×500 mm, which is enclosed by the wall ofthe treatment chamber (2) in the top view of the treatment chamber issprayed into the treatment chamber (2) during the fresh-water rinsephase and water quantity of 0.10 to 0.15 litres per unit area of 500mm×500 mm, which is enclosed by the wall of the treatment chamber (2) inthe top view of the treatment chamber is conducted in steam form duringthe steam rinse phase into the treatment chamber (2).
 14. Dishwasheraccording to claim 11, characterized in that the treatment chamber (2)is designed to accommodate at least one basket of 500 mm×500 mm. 15.Dishwasher according to claim 11, characterized in that the fresh-watersupply device (21) for heating the rinse liquid to be conveyed into thetreatment chamber (2) during the fresh-water rinse phase has a boiler(21) which is connected to a fresh-water feed line (28) and the outlet(35) of which is connected to the intake side of a first rinse pump(12), of which there is at least one.
 16. Dishwasher according to claim11, characterized in that the fresh-water supply device (14) has afresh-water tank (14) which is connected to a fresh-water line (31) andthe outlet (36) of which is connected to the intake side of a secondrinse pump (13), of which there is at least one.
 17. Dishwasheraccording to claim 11, characterized in that the steam generator (20) isintegrated in the boiler (21); and a steam outlet (23) of the steamgenerator (20) is connected to the treatment chamber (2) via a steamline (32), which is separate from the rinse line system (15) and thewash line system (10), at a location (37) which is higher than the tank(4).
 18. (canceled)
 19. Dishwasher according to claim 11, characterizedin that the program-control device (50) is designed to execute acondensation and draining phase which follows the steam rinse phase andwhich lasts for a defined time during which steam which has condensed inthe treatment chamber (2) can flow down into the tank (4) after thesteam rinse phase, before the end of the program is reached. 20.Dishwasher according to claim 11, characterized in that a rinse-aidmetering device is provided for metering rinse aid into the fresh waterof the rinse liquid.
 21. Dishwasher according to claim 11, characterizedby a return-prevention means (16) via which the intake end of the atleast one rinse pump (12, 13) is connected to a fresh-water feed line(17), with the back flow-prevention means (16) being designed to preventliquid from flowing back into the fresh-water feed line (17) in thedirection from the at least one rinse pump (12, 13).
 22. Dishwasheraccording to claim 11, characterized by a water-softening device (39)for conditioning the fresh water for the fresh-water rinse system (12,13, 15 a, 15 b, 33, 34) and the fresh water for the steam rinse system(20, 32).